LF2 - Foam Dart Blaster (Nerf)

This is a redesign of the legendary LF1 Foam Dart Blaster, one of the oldest Nerf compatible printed guns on Thingiverse. Aspects of the design that I liked were carried over (the use of PVC pipe for the plunger bore), and I attempted to remedy some of the design's shortcomings:

• The "chamber" is a printed assembly with threaded ends to ensure sealing/collinearity.
• Dual seals on the plunger, and designed so that parts are all in compression or tension.
• Aesthetics upgraded significantly (or so I hope :D).
• Stronger plunger spring used here.
• Identical trigger and catch springs.

This design is very robust. It can likely handle much higher spring compression.

I will eventually get around to adding a different bolt that compresses the spring even further for MORE POWA. Also may release an M3/M4 version since 10-32 is definitely overkill...and imperial heh.

Instructions

3D Printed Parts:

Ensure your printer is well tuned. The plunger to bolt carrier interface is tight.

Chamber, Chamber Cap, Barrel, Plunger:

Print vertically and with supports. I use PETG on these parts for impact absorption and layer adhesion. I had to clean out the o-ring grooves on the plunger.

Bolt Carrier, Bolt Handle:

Print the carrier flat with the notch and handle bolt holes facing the side (you want these details facing the side as to load them across all layers). Use supports. Print the handle with the loop flat on the build plate. Use PETG here as well, we don't want brittle failures.

Grips, Catch, Trigger: I used PETG, up to you. Print all of these laying flat.

Spring Post Halves: If you're a perfectionist, print these and glue them to the opposing face of the shell half with the relief cuts to better seat the trigger and catch springs. You'll see what I mean.

Shell Halves: Print flat. I used PLA+ due to their size, no brim. I was having PETG warping issues. You will have to clear out support material from the interior of the gun, I had no issues.

Non-3D Printed Parts:

Hardware:

(10) 10-32 Button Head Screws, 1inch long

(10) 10-32 Hex Nuts

McMaster-Carr:

(2) 9434K25 - Music-Wire Steel Compression Springs 0.5" Long, 0.18" OD, 0.144" ID

(1) 9657K436 - Compression Spring 3" Long, 0.72" OD, 0.576" ID

(1) 48925K92 - 3/4" Sch. 40 PVC 4in long

(2) 9452K26 - Oil-Resistant Buna-N O-Ring 3/32 Fractional Width, Dash Number 114

Assembly:

Chamber Assembly:

Pull the Bolt Carrier through the Plunger so they interface.

Put o-rings on Plunger. LUBRICATE IT.

Thread Barrel onto Chamber.

Drop in cut-to length PVC pipe into chamber.

Drop in Plunger w/ o-rings + Bolt Carrier into the chamber (lined with PVC).

Drop in spring to rest on back of Plunger.

Thread Chamber Cap onto the Chamber, compressing the spring.

Blaster Assembly:

Glue your spring post halves to Shell_R (optional step).

Insert Trigger, with spring.

Slide Catch onto the protruding part of Bolt_Carrier.

Insert Catch with spring, while attached to Chamber Assembly.

Drop in the Chamber Assembly into Shell_R, ensuring proper orientation of Bolt_Carrier (notch for Catch facing top of gun). Ensure the barrel sight is vertical as well.

Pray no springs launch components.

Hastily slam Shell_L over all the mess.

Thread on Handle and Grips, and never open it again. Hopefully.